 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
MC34674B Datasheet(PDF) 18 Page - Freescale Semiconductor, Inc |
|
||||||||||||||||||||||||||||||
MC34674B Datasheet(HTML) 18 Page - Freescale Semiconductor, Inc |
|
|
18 / 26 page  Analog Integrated Circuit Device Data 18 Freescale Semiconductor 34674 FUNCTIONAL DESCRIPTION FUNCTIONAL DEVICE OPERATION BATTERY CONNECTION VERIFICATION Battery connection verification is to ensure that the battery is properly connected before the charging starts. The charger does not start if the battery is short-circuited or open- circuited. A fault indication is issued if the battery is not connected properly. During the connection fault state, the connection verification operates every 2 seconds in order for the charger to recognize a newly inserted battery within 2 seconds. The verification utilizes the fact that a battery voltage cannot change very fast when being charged or discharged. The charger first discharges the battery with 6mA current for 250ms. If the battery voltage does not fall below the 1.5V threshold, then the battery is connected. Otherwise, the charger charges the battery. If the voltage moves above the recharge threshold or stays below 1.5V within 250ms, then the battery is not connected properly (either open-circuited or short-circuited). Figure 21 shows the flow chart for the battery connection verification. The MC34674 has a built-in mechanism to detect if the battery is removed within 1.968 seconds during the charge completion state. Figure 22 shows the simplified analog circuit for this function. In each 1.968 second period, the MC34674 tries to discharge the output with a 585 µA current for 82ms. If during the 82ms, the output voltage drops below the recharge threshold, the charger will enter the battery connection verification state. Otherwise, the charger remains in the charge completion state. To compensate for the discharge caused by the 585 µA current, the charger outputs a 24 µA current to the output during the whole 1.968 seconds. Both the current and time values for this purpose are well matched, the net output current is guaranteed within -4 µA to +2 µA to the output. Figure 22. Simplified Battery Removal Detection Circuit. THERMAL REGULATION The charger has an internal thermal regulation loop. When the internal temperature reaches 110°C, the charger starts to reduce the charge current to prevent further temperature rise. The current is reduced just enough to maintain the internal temperature at 110°C. The thermal regulation loop removes the concern of thermal failure. INTERNAL TIMER An internal timer is offered to set the time reference for the charge time limit. The fast charge time is limited to 4.6 hours (typ.) and the trickle-charge time is limited to 1/8 of the above time. FLEXIBLE LED INDICATION The MC34674 has multiple LED indication schemes built in. Consult Freescale for additional indication schemes. CURRENT-LIMITED AC/DC REGULATOR The MC34674 has a special low thermal charging operation when powered with a current-limited ac/dc regulator. In the operation, the charge current is limited by the ac/dc regulator and the MC34674 operates as a switch during the CC-mode to minimize the heat generation. Refer to the Typical Applications section for more details. ON OFF BAT 24uA 585uA COUT |
Similar Part No. - MC34674B |
|
Similar Description - MC34674B |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
